Bugs: Cotton stainers (Dysdercus spp.)
Several species of bugs attack okra. Some of them occur from the early stages of the crop, but are more common during the mature stages, feeding on developing pods. Their feeding causes small, dark, raised blister-like spots on pods.
These bugs are very common on okra plants at the fruiting stage. They are conspicuously red with black bands. Both adults and nymphs feed on developing pods and seeds, piercing them to suck sap, thereby reducing yield. Attacked young fruits shrivel and then dry. Feeding on mature fruits results in damage to the seeds. Stainers also attack cotton and they live on baobab and silk cotton (kapok) trees.
Stainer bugs are between 14 and 24 mm long.
- Plough deeply or hoe to expose the eggs.
- Uproot all plants after harvesting and destroy wild alternate hosts.
- Custard apple leaf extract is recommended for control of these bugs (PAN).
- Preventive control measures are sanitation; remove plants and all its debris as soon as harvesting is over. Keep stores clean. Hand pick and destroy the bugs, this is feasible in small plots and at the beginning of infestations, and will help to reduce population density.
- Caging chickens in cotton plots using chicken wire may control cotton stainers; about 15 birds will keep about 0.1 ha free of stainer bugs. This is a good option for small plots grown next to the homestead.
- Cotton stainers are attacked by a range of natural enemies; the most important are assassin bugs, ants, spiders, birds and parasitic flies.
- The baobab tree is one of the main host plants of stainer bugs. If cotton is grown where baobab occurs, the soil and trunk of the baobab tree should be sprayed with biopesticides to kill the nymphs hatching from eggs laid around the stem.
- Tanzania: Pyrethrum formulation is used with black wattle extract as UV light stabiliser